Esophageal stent including a valve member

ABSTRACT

An example medical device is disclosed. An example medical device includes an expandable stent. The stent includes a tubular scaffold formed of one or more interwoven filament. The tubular scaffold includes an inner surface and a flexible valve extending radially inward from the inner surface of the scaffold. Further, the valve is configured to shift between a closed configuration and an open configuration and the one or more filaments of the scaffold bias the valve to the closed configuration while in a nominally deployed state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 16/176,451, filedOct. 31, 2018, which application claims priority under 35 U.S.C. § 119to U.S. Provisional Application Ser. No. 62/579,990, filed Nov. 1, 2017,the entirety of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure pertains to medical devices, methods formanufacturing medical devices, and uses thereof. More particularly, thepresent disclosure pertains to stents including a valve, such as ananti-reflux valve, and methods for manufacturing and using such stents.

BACKGROUND

The lower esophageal sphincter is a muscle located between the esophagusand the stomach. The sphincter normally functions as a one-way valve,allowing material (e.g., food) that travels downward through theesophagus to enter the stomach while preventing the backflow (reflux) ofhydrochloric acid and other gastric contents into the esophagus.However, in some cases the lower esophageal sphincter does not closeadequately, and therefore, permits stomach acid to reflux into theesophagus, causing heartburn. A weak or inoperable lower esophagealsphincter is a major cause of gastroesophageal reflux disease (GERD).

Therefore, a variety of intracorporeal medical devices have beendeveloped to treat gastroesophageal disease caused by a malfunctioninglower esophageal sphincter. For example, elongated stents incorporatingflexible valves have been developed to allow material (e.g., food) totravel through the esophagus and enter the stomach while also preventingstomach acid to reflux into the esophagus. However, there is an ongoingneed to provide alternative configurations of and/or methods of formingstents including a two-way valve to treat gastroesophageal disease, aswell as other medical conditions.

BRIEF SUMMARY

This disclosure provides design, material, manufacturing method, and usealternatives for medical devices. An example medical device includes anexpandable stent. The stent includes a tubular scaffold formed of one ormore interwoven filament. The tubular scaffold includes an inner surfaceand a flexible valve extending radially inward from the inner surface ofthe scaffold. Further, the valve is configured to shift between a closedconfiguration and an open configuration and the one or more filaments ofthe scaffold bias the valve to the closed configuration while in anominally deployed state.

Alternatively or additionally to any of the embodiments above, whereinthe valve shifts from the closed configuration to the open configurationdue to a peristaltic force applied to the tubular scaffold.

Alternatively or additionally to any of the embodiments above, whereinthe valve includes a valve opening extending therethrough, and whereinthe valve opening is ovular-shaped in the open configuration.

Alternatively or additionally to any of the embodiments above, whereinthe tubular scaffold includes a first tapered region and a secondtapered region, and wherein the valve is positioned between the firsttapered region and the second tapered region.

Alternatively or additionally to any of the embodiments above, whereinthe first tapered region is configured to funnel material toward thevalve.

Alternatively or additionally to any of the embodiments above, whereinthe one or more filaments of the scaffold are configured to radiallyexpand to shift the valve from the closed configuration to the openconfiguration when subjected to a radial expansion force of 0.800 N/cm²or greater.

Alternatively or additionally to any of the embodiments above, furthercomprising a coating disposed along the one or more filaments, andwherein the valve is formed from a portion of the coating.

Alternatively or additionally to any of the embodiments above, the valveis a two-way valve configured to permit material to pass through thevalve in a first direction and a second direction, and wherein the firstdirection is opposite the second direction.

An example method of manufacturing a stent includes forming a tubularscaffold, wherein the tubular scaffold includes a first end, a secondend and a narrowed region positioned between the first end and thesecond end. The tubular scaffold is positioned on a coating mandrel suchthat the coating mandrel radially expands the narrowed region such thatthe tubular scaffold is spaced away from the coating mandrel at thenarrowed region. A coating is applied to the tubular scaffold while thetubular scaffold is positioned on the coating mandrel. Applying thecoating to the tubular scaffold includes forming a valve within thenarrowed region of the tubular scaffold. Thereafter, the tubularscaffold is removed from the coating mandrel and the tubular scaffoldradially collapses at the narrowed region to bias the valve in a closedconfiguration after being removed from the coating mandrel.

Alternatively or additionally to any of the embodiments above, whereinforming the tubular scaffold comprises braiding at least two or morestent filaments together.

Alternatively or additionally to any of the embodiments above, whereinforming the tubular scaffold further comprises positioning the tubularscaffold on a shaping mandrel, and wherein the shaping mandrel isconfigured to radially pinch the one or more filaments to create thenarrowed region.

Alternatively or additionally to any of the embodiments above, whereinforming the tubular scaffold further comprises heat treating the tubularscaffold while the tubular scaffold is positioned on the shapingmandrel.

Alternatively or additionally to any of the embodiments above, whereinapplying the coating to the tubular scaffold further includes sprayingthe coating on the tubular scaffold.

Alternatively or additionally to any of the embodiments above, whereinthe valve has an ovular-shaped opening in an open configuration.

Another example expandable stent includes a braided tubular scaffoldformed of a plurality of interwoven filaments. The tubular scaffoldincludes a first end, a second end and a lumen extending therethrough.The tubular scaffold further includes a narrowed region positionedbetween the first end and the second end. A flexible valve is positionedwithin the lumen at the narrowed region. The plurality of interwovenfilaments apply a radially compressive force on the valve to bias thevalve to a closed configuration while the stent is in a nominallydeployed state.

Alternatively or additionally to any of the embodiments above, whereinthe radially compressive force is less than or equal to 0.800 N/cm².

Alternatively or additionally to any of the embodiments above, whereinthe narrowed region includes a first diameter while in the nominallydeployed state, and wherein the narrowed region is configured toradially expand to open the valve when subjected to a radially expandingforce of 0.800 N/cm² or greater.

Alternatively or additionally to any of the embodiments above, whereinthe valve shifts from the closed configuration to an open configurationdue to a peristaltic force applied to the plurality of interwovenfilaments.

Alternatively or additionally to any of the embodiments above, whereinthe valve includes a valve opening extending therethrough, and whereinthe valve opening is ovular-shaped in the open configuration.

Alternatively or additionally to any of the embodiments above, furthercomprising a coating disposed along the plurality of filaments, andwherein the valve is formed from a portion of the coating.

The above summary of some embodiments is not intended to describe eachdisclosed embodiment or every implementation of the present disclosure.The Figures, and Detailed Description, which follow, more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of thefollowing detailed description in connection with the accompanyingdrawings, in which:

FIG. 1 is an example stent;

FIG. 2 is a cross-sectional view of the stent of FIG. 1 including avalve;

FIGS. 3 and 4 are cross-sectional views of the stent of FIG. 1illustrating material passing through the valve;

FIG. 5 is an enlarged cross-sectional view of a portion of the stent ofFIG. 1 including the valve in a closed configuration;

FIG. 6 is a cross-sectional view of the stent and valve of FIG. 5 takenalong line 6-6 of FIG. 5 ;

FIG. 7 is an enlarged cross-sectional view of a portion of the stent ofFIG. 1 including the valve in an open configuration;

FIG. 8 is a cross-sectional view of the stent and valve of FIG. 7 takenalong line 8-8 of FIG. 7 ;

FIG. 9 is a cross-sectional perspective view of an example shapingmandrel and fixture device;

FIG. 10 is another cross-sectional view of the shaping mandrel andfixture device shown in FIG. 9 ;

FIG. 11 is a cross-sectional view of the shaping mandrel and fixturedevice shown in FIG. 9 with a stent positioned thereon;

FIGS. 12-13 illustrate an example manufacturing method for forming avalve within an example stent; and

FIG. 14 is an example stent delivery system;

FIG. 15 is a plan view of the stent delivery system shown in FIG. 14with the outer member retracted;

FIG. 16 is a cross-sectional view of the stent and valve of FIG. 15taken along line 16-16 of FIG. 15 ;

FIG. 17 illustrates an example test fixture;

FIG. 18 illustrates an example testing step of the example test fixtureshown in FIG. 17 ;

FIG. 19 illustrates another example testing step of the example testfixture shown in FIG. 17 .

While the disclosure is amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit the disclosureto the particular embodiments described. On the contrary, the intentionis to cover all modifications, equivalents, and alternatives fallingwithin the spirit and scope of the disclosure.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (e.g., having the same function orresult). In many instances, the terms “about” may include numbers thatare rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

It is noted that references in the specification to “an embodiment”,“some embodiments”, “other embodiments”, etc., indicate that theembodiment described may include one or more particular features,structures, and/or characteristics. However, such recitations do notnecessarily mean that all embodiments include the particular features,structures, and/or characteristics. Additionally, when particularfeatures, structures, and/or characteristics are described in connectionwith one embodiment, it should be understood that such features,structures, and/or characteristics may also be used connection withother embodiments whether or not explicitly described unless clearlystated to the contrary.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of thedisclosure.

Gastroesophageal reflux disease (GERD) is a medical condition wherebystomach acids enter the lower portion of the esophagus because the loweresophageal sphincter (positioned at the entrance of the stomach) failsto close properly. In some instances, the lower esophageal sphincter'sinability to close is due to disease or general atrophy. When left open,the sphincter may permit reflux of stomach acids into the esophagus,causing severe heartburn and potentially contributing to the onset ofother diseases.

One method of treating GERD is to place an anti-reflux stent into theentrance of the stomach. An anti-reflux stent may include an expandabletwo-way valve which allows food and liquid to enter the stomach butlimits liquids (stomach acids) from passing back through the valve undernormal digestive conditions (e.g., the valve may permit liquids to passback through the valve during periods then the stomach contracts topermit vomiting). In general, there is an ongoing need for ananti-reflux stent to provide a smooth lumen opening into the stomachwhile limiting stomach acids from passing back through the valve andinto the esophagus.

FIG. 1 shows an example stent 10. Stent 10 may include a tubularscaffold 22 having a first end, which may extend to the first end of thestent 10, a second end, which may extend to the second end of the stent10, and a lumen extending therethrough. The tubular scaffold 22 may beconfigured to provide the support structure for stent 10. The tubularscaffold 22 may be formed of one or more stent filaments 14, or aplurality of stent filaments 14. Filaments 14 may extend longitudinallyalong stent 10. In some instances, filaments 14 may extendlongitudinally along stent 10 in a helical fashion. While FIG. 1 showsfilaments 14 extending along the entire length of stent 10 between firstand second ends of stent 10, in other examples, the filaments 14 mayextend only along a portion of the length of stent 10.

Additionally, FIG. 1 shows example stent 10 including one or moreenlarged portions (e.g., flanges) 12 proximate the first end 21 andsecond end 23 of the stent 10. In some instances, enlarged portions 12may be defined as an increase in the outer diameter, the inner diameteror both the inner and outer diameter of stent 10 relative to a medialregion of the stent 10. The enlarged portions 12 may be beneficial toanchor the stent within the esophagus and/or the opening to the stomach.Additionally, as will be described in greater detail below, FIG. 1illustrates stent 10 including a first tapered portion 17, a secondtapered portion 19 and a narrowed region 11 positioned between the firsttapered portion 17 and the second tapered portion 19. First taperedportion 17 may taper toward the narrowed region (i.e., neck) 11 from alarger diameter to a smaller diameter, while second tapered portion 19may taper toward the narrowed region (i.e., neck) 11 from a largerdiameter to a smaller diameter.

In some instances, stent 10 may be a self-expanding stent.Self-expanding stent examples may include stents having one or moreinterwoven filaments 14 to form a tubular scaffold 22, having openingsdefined between adjacent filaments 14. For example, stent filaments 14may be wires braided, knitted or otherwise interwoven to form thetubular scaffold 22. Openings or interstices through the wall of thetubular scaffold 22 may be defined between adjacent stent filaments 14.Alternatively, tubular scaffold 22 of stent 10 may be a monolithicstructure formed from a cylindrical tubular member, such as a single,cylindrical tubular laser-cut Nitinol tubular member, in which theremaining portions of the tubular member form the stent filaments 14with openings defined therebetween.

Stent 10, or components thereof, (including tubular scaffold 22 and/orstent filaments 14) disclosed herein may be constructed from a varietyof materials. For example, stent 10 (e.g., self-expanding or balloonexpandable), or components thereof, may be constructed from a metal(e.g., Nitinol). In other instances, stent 10 or components thereof maybe constructed from a polymeric material (e.g., PET). In yet otherinstances, stent 10, or components thereof, may be constructed from acombination of metallic and polymeric materials. Additionally, stent 10,or components thereof, may include a bioabsorbable and/or biodegradablematerial.

Additionally, stent 10 may include one or more coating layers disposedon tubular scaffold 22, such as positioned on and/or adjacent to theinner surface and/or outer surface thereof. The coating layer may bepositioned on a portion of filaments 14 forming tubular scaffold 22 andextend across openings or cells between adjacent filaments 14. Forexample, FIG. 2 shows stent 10 including a coating layer 20 disposedalong the inner surface of tubular scaffold 22. In some instances,coating layer 20 may be an elastomeric or non-elastomeric material. Forexample, coating layer 20 may be a polymeric material, such as silicone,polyurethane, or the like. Further, the coating layer 20 may span thespaces (e.g., openings, cells, interstices) in the wall of tubularscaffold 22 defined between adjacent filaments 14. For example, thecoating layer 20 may extend along and cover the inner surface and/orouter surface of tubular scaffold 22 such that the coating layer 20spans one or more of spaces (e.g., openings, cells, interstices) betweenfilaments 14 in the wall of tubular scaffold 22.

As described above, stent 10 may have a first end 21 and a second end23. When positioned in a body lumen (e.g., esophagus) first end 21 maybe defined as the proximal end of stent 10 and oriented as the end ofstent 10 closest to a patient's mouth and second end 23 may be definedas the distal end of stent 10 and oriented as the end of stent 10closest to a patient's stomach. In some examples, a first end region ofstent 10 extending proximal of a proximal most flange 12 may be longerthan a second end region of stent 10 extending distal of a distal mostflange 12. The additional length of first end region may extend into andcover the lower esophagus in the event a small amount of stomach acidwere to leak through the valve 16 (shown in FIG. 2 ).

As shown in FIG. 2 , coating layer 20 may extend along the length oftubular scaffold 22 from first end 21 to second end 23. In other words,in some instances coating layer 20 may be defined as a continuous layerthat extends from first end 21 to second end 23 of stent 10 and fullyextends across and fills cells or interstices defined between filaments14 of tubular scaffold 22. However, in other instances coating layer 20may extend less than the entire length of stent 10, if desired, leavinga portion of cells or interstices defined between filaments 14 oftubular scaffold 22 unfilled or open.

Additionally, FIG. 2 shows a valve 16 positioned within the lumen ofstent 10. As will be discussed in greater detail below, valve 16 may beformed as a portion of coating layer 20. In other words, valve 16 may bea unitary or monolithic structure formed in conjunction with formingcoating layer 20 on tubular scaffold 22. For example, FIG. 2 illustratesthat valve 16 may be an inwardly extending portion of coating layer 20extending radially inward of tubular scaffold 22 at narrowed or neckedregion 11. In other words, valve 16 may be defined as a unitary ormonolithic portion of coating layer 20 that extends radially inward froman inner surface of tubular scaffold 22 toward the central longitudinalaxis 25 of stent 10.

Further, in some examples, valve 16 may be defined as a monolithicportion of coating layer 20 that extends circumferentially within thelumen of stent member 10. In other words, it can be appreciated thatvalve 16 may be defined as an annular member that extends continuouslyaround the lumen of stent 10 positioned radially inward of tubularscaffold 22 in the narrowed or necked region 11. Further, valve 16 maybe defined as an uninterrupted extension of coating layer 20 projectingtoward central longitudinal axis 25, forming an annular rim of polymericmaterial radially inward of tubular scaffold 22 in the narrowed ornecked region 11.

As described above, FIG. 2 illustrates that stent 10 may include a firsttapered (e.g., conical) region 17 and a second tapered (e.g., conical)region 19 with the narrowed or necked region 11 positioned therebetween.Both first conical region 17 and second conical region 19 may generallybe shaped to taper radially inwardly in opposite directions toward thelongitudinal axis 25 providing the stent 10 with an hourglass shape. Forexample, first conical region 17 may taper radially inward from a firsttransition point 13 along stent 10 to valve 16 while second conicalregion 19 may taper radially outward from valve 16 to a secondtransition point 15 along stent 10. For example, the first conicalregion 17 (including the stent filaments 14 and coating layer 20) maybear some resemblance to a cone-shaped funnel tapering from a wideportion nearest a patient's mouth to valve 16. Further, second conicalregion 19 (including the stent filaments 14 and coating layer 20) maybear some resemblance to a cone-shaped funnel tapering from valve 16 toa wide portion closer to a patient's stomach. Further, as illustrated inFIG. 2 , in a closed configuration, valve 16 may taper inwardly towardcentral longitudinal axis 25 and close (e.g., contact, seal, etc.) ontoitself such that it stops flow of material (e.g., stomach acid) fromflowing through the lumen of stent 10. As discussed above, it may bedesirable for valve 16 to prevent stomach acids from flowing from apatient's stomach toward the patient's mouth. FIG. 2 shows valve 16 in aclosed configuration. The stent 10 may be configured to bias valve 16 tothe closed configuration in a nominally deployed state.

As described above, in some instances it may be desirable for valve 16to expand radially outward to permit nutritional material (e.g., food,water, etc.) to pass through the lumen of stent 10. For example, in someexamples it is desirable for valve 16 to radially expand to permit abolus of food or liquid to pass from a patient's mouth, through thevalve 16, to the stomach. As will be described in greater detail below,at least some stent and valve examples disclosed herein may includestent filaments of tubular scaffold 22 which impart a radiallycompressive force inward on valve 16 to maintain the valve 16 in aclosed configured while in a “nominally-deployed” state (e.g., a statein which no outside forces are acting on the stent 10 to move the valve16 to an open configuration).

Further, the compressive force exerted by filaments 14 of tubularscaffold 22 on valve 16 must be low enough such that normal, peristalticcontractions associated with normal digestive processing (e.g., normaleating and digesting of food) will open valve 16, thereby permitting thebolus of nutritional material to pass through valve 16 and into thestomach (while also permit vomiting contractions to expel food backthrough valve 16). However, this compressive force must also be largeenough to ensure the valve 16 reverts to the closed configuration whenin the nominally deployed state such that stomach acids will not leakthrough the valve 16 from the stomach, causing symptoms of acid reflux.

Therefore, in at least some examples a threshold radially inwardcompressive force may be imparted by the filaments 14 onto the valve 16in the nominally deployed state to hold the valve 16 in the closedconfiguration. In other words, stent 10 (including the radialcompression of filaments 14) must be designed such that valve 16 remainsclosed in a nominally deployed state, yet opens when peristatic forcesgreater than the threshold inward compressive force are imparted ontothe valve 16 (e.g., when peristaltic forces push a bolus of food orliquid through the valve aperture 124, thereby causing radially outwardexpansion forces of greater than the threshold inward compressive forceto be imparted to the scaffold 22) to overcome the radially inwardlycompressive forces biasing the valve 16 to the closed configuration. Insome instances, the threshold inward compressive force may be less than0.900 N/cm², less than 0.800 N/cm², less than 0.700 N/cm², less than0.600 N/cm², less than 0.500 N/cm², or less than 0.400 N/cm².Furthermore, forces less than the threshold inward compressive force(such as those imparted onto the valve 16 via acid reflux) will notcause valve 16 to open, thereby preventing stomach acids from flowingfrom the stomach into the esophagus. In some instances, the thresholdinward compressive force may be at least 0.200 N/cm², at least 0.300N/cm², at least 0.400 N/cm², at least 0.500 N/cm², at least 0.600 N/cm²,at least 0.700 N/cm², or at least 0.800 N/cm². In some instances, thethreshold inward compressive force may be in the range of between 0.200N/cm² to 0.900 N/cm², in the range of between 0.200 N/cm² to 0.800N/cm², in the range of between 0.300 N/cm² to 0.900 N/cm², in the rangeof between 0.300 N/cm² to 0.800 N/cm², in the range of between 0.400N/cm² to 0.800 N/cm², in the range of 0.400 N/cm² to 0.700 N/cm², forexample.

FIG. 3 and FIG. 4 illustrate valve 16 expanding radially outward toallow a bolus of nutritional material (e.g., food) 18 to pass throughthe lumen of stent 10 and through valve 16. As shown by the arrow inFIG. 3 , and, in general, bolus of nutritional material 18 may flowthrough stent 10 from a first end 21 (e.g., the end closest to apatient's mouth) to a second end 23 (e.g., the end closest to apatient's stomach). FIG. 4 illustrates that valve 16 may permit thematerial 18 to pass through the lumen of the stent 10 by expandingradially outward as the material 18 passes through valve 16. While notshown in FIG. 4 , it is contemplated that in some examples valve 16 mayconform to the shape of material 18 as it passes through valve 16.

FIG. 5 illustrates an enlarged and detailed view of example stent 10including tubular scaffold 22 and valve 16. As described above, stent 10may include a coating layer 20 covering tubular scaffold 22 and formingvalve 16. For example, FIG. 5 illustrates that coating layer 20 mayinclude a thickness depicted as “X” extending along a substantialportion and covering filaments 14, such as covering an inner surfaceand/or outer surface of filaments 14. For illustrative purposes, coatinglayer 20 is shown extending along inner surface of tubular scaffold 22,however, it is noted that additionally or alternatively coating layer 20may extend along outer surface of tubular scaffold in some embodiments.In some examples, the coating layer 20 may be formed from a siliconematerial or a polyurethane material, for instance.

Further, as shown in FIG. 5 (and illustrated further in FIG. 6 ), thecoating layer 20 may extend radially inward from the inner surface oftubular scaffold 22 to form the valve 16 at narrowed or necked region 11of stent 10. As will be further illustrated in FIG. 6 , valve 16 mayhave an annular shape and include a circumferential, curvilinear surfaceextending around the longitudinal axis 25 of stent 10 whereby thecoating layer 20 extends away from the inner surface of the wall of thetubular scaffold 22 (e.g., radially inward toward the longitudinal axis25) to form valve 16. As illustrated in FIG. 5 , valve 16 may include athickness depicted as “Y” in FIG. 5 .

FIG. 5 illustrates that in some instances the thickness “Y” of valve 16may be substantially equal to the thickness “X” of coating layer 20. Inother words, coating layer 20 may maintain a substantially uniformthickness “X” along the length of scaffold 22 which extends uniformly toform the thickness “Y” of valve 16. However, in other embodiments thewall thickness “X” of coating layer 20 and/or the thickness “Y” definingvalve 16 may be different. For example, some portions of coating layer20 and/or the thickness defining valve 16 may be thinner or thicker thanother portions along stent 10.

Similar to that shown in FIG. 2 , FIG. 5 illustrates the first taperedregion 17 and the second tapered region 19, both of which may bear someresemblance to a cone-shaped funnel and together form an hourglassshape. For example, stent 10 (including tubular scaffold 22 and coatinglayer 20) may taper radially inward from a first transition point 13toward valve 16. Valve 16 includes a valve aperture 24. Valve aperture24 may be defined as the “opening” of valve 16 (e.g., the opening ofvalve 16 through which nutritional material may flow). As illustrated inFIG. 5 , valve aperture 24 may be aligned with the central longitudinalaxis 25.

FIG. 5 further illustrates stent 10 (including scaffold 22 and coatinglayer 20) tapering radially inward from a second transition point 15toward valve 16. Further, both the first tapered region 17 and thesecond tapered region 19 may include a wide portion having an innerdiameter (depicted in FIG. 5 as dimension “W”) tapering to a narrowerportion having an inner diameter (depicted in FIG. 5 as dimension “Z”)less than the inner diameter of the wide portion. As shown in FIG. 5 ,the wide portion of each of the first tapered region 17 and the secondtapered region 19 may be positioned adjacent to first transition point13 and second transition point 15, respectively. Further, the narrowerportion may be positioned closer to valve 16.

FIG. 6 shows a cross-sectional view of stent 10 through narrowed region11 and valve 16 taken along line 6-6 of FIG. 5 . In particular, line 6-6of FIG. 5 intersects valve aperture 24 of valve 16 described above. Asshown in FIG. 6 , valve aperture 24 may intersect the longitudinal axis25 of stent 10. As described above, FIG. 6 depicts valve 16 in a closedconfiguration whereby filaments 14 (defining scaffold 22 describedabove) are imparting a radial inward compressive force onto valve 16,thereby maintaining valve aperture 24 in a closed configuration. FIG. 6illustrates that narrowed region 11 of stent 10 may include an outerdiameter which is depicted as “D_(C)” in FIG. 6 in the closedconfiguration. The closed configuration of valve 16 may be defined as aconfiguration which the valve aperture 24 is closed and preventsmaterial from flowing through the valve aperture 24. As described above,FIG. 6 shows the shape of valve 16 as substantially circular andextending circumferentially around the longitudinal axis 25 of the stent10.

FIG. 7 shows an enlarged view of stent 10 described above with valve 16in an open configuration. For example, FIG. 7 shows valve aperture 24opened to a width depicted as dimension “V” in FIG. 7 . As discussedabove, it can be appreciated that valve aperture 24 may open via a forcebeing imparted radially outward (e.g., a force generated via nutritionalmaterial being driven through the valve 16 via peristalsis) which islarge enough to overcome the radially inward compressive force(described above) imparted by filaments 14 of tubular scaffold 22described above.

FIG. 8 shows a cross-sectional view of the stent 10 through narrowedregion 11 and valve 16 taken along line 8-8 of FIG. 7 . FIG. 8 furtherillustrates the valve 16 in an open configuration. In other words, FIG.8 shows narrowed region 11 of stent 10 being expanded to an outerdiameter depicted as “D_(O)” in FIG. 8 . Diameter D_(O) may be greaterthan diameter D_(C) described above with respect to FIG. 6 . It can beappreciated that as narrowed region 11 of stent 10 expands due toperistaltic forces acting thereupon, the outer diameter of narrowedregion of stent 10 may increase from diameter D_(C) depicted in FIG. 6to diameter D_(O) depicted in FIG. 8 . Accordingly, as the outerdiameter of narrowed region of stent 10 increases from diameter D_(C)depicted in FIG. 6 to diameter D_(O) depicted in FIG. 8 , valve 16(including valve aperture 24) may shift from a closed configuration toan open configuration. Likewise, tubular scaffold 22 radially expands innarrowed region 11 between the closed configuration to the openedconfiguration.

Additionally, line 8-8 of FIG. 7 transects the valve aperture 24described above. FIG. 8 illustrates the valve 16 extending radiallyinward from stent filaments 14 (defining scaffold 22 described above).As shown in FIG. 8 , valve aperture 24 may be an opening centered aboutthe central longitudinal axis 25 of the lumen of stent 10. However,while the figures described herein depict example valves and relatedelements centered about the central longitudinal axis 25, it iscontemplated that any of the examples described herein may be designedsuch that the structural elements defining any portion of stent 10and/or valve 16 may be off-center. In other words, valve 16 may beasymmetrical about the central longitudinal axis 25 in one or moreexamples described herein.

Additionally, FIG. 8 shows that valve aperture 24 may be substantiallyovular (e.g., elliptically) shaped in the open configuration. The ovularshape of the valve aperture 24 may reduce the force required to maintainvalve 16 in closed configuration while also permitting valve 16 to openvia peristaltic forces acting upon valve 16 as described above. Whilethe example shown in FIG. 8 illustrates an ovular-shaped valve aperture24, other examples are contemplated in which the shape of valve aperture24 may be circular, triangular, star-shaped, square, rectangular, etc.Additionally, in some examples the valve aperture 24 may include one ormore structures including flaps, leaflets, channels, slits, cuts,grooves, etc. Further, valve aperture 24 designs which combine thevarious geometric shapes, orientations and structures are contemplated.

FIGS. 9-11 illustrates an example device and method for forming (e.g.,heat setting) the stent structure including stent scaffold 22 formedfrom filaments 14 as shown and described above. For example, FIG. 9illustrates an example stent shaping mandrel 44 which is mounted on(e.g., engaged with) an external stent fixture device 42. As illustratedin FIG. 9 , stent shaping mandrel 44 may include a first mandrel segment41 and a second mandrel segment 43. External stent fixture 42 may holdfirst mandrel segment 41 in a fixed position relative to second mandrelsegment 43 with a gap between first mandrel segment 41 and secondmandrel segment 43 such that first mandrel segment 41 is spaced awayfrom second mandrel segment 43 and not directly contacting one another.Additionally, shaping mandrel 44 may further include a compressivemember 45. Compressive member 45 may be positioned in the gap betweenthe first mandrel segment 41 and the second mandrel segment 43.Compressive member 45 may include a narrowed aperture (e.g., opening,pinch point, etc.) 52. In some instances, compressive member 45 maycomprise a plurality of circumferentially arranged diescircumferentially arranged about a central longitudinal axis extendingthrough first and second mandrel segments 41, 43. The plurality of diesmay be radially movable toward and away from central longitudinal axisto adjust the size of the narrowed aperture 52.

As will be illustrated and described below, stent shaping mandrel 44 maybe utilized to change the shape (e.g., form) of a straight, cylindricaltubular, braided stent scaffold into a more complex-shaped stentscaffold such as stent scaffold 22 shown in FIG. 1 (which includesenlarged portions 12, tapered portions 17/19 and narrowed region 11). Inorder to form the complex scaffold 22 shape illustrated in FIG. 1 , itmay be desirable to utilize a stent fixture device 42 to manipulate thevarious components of the shaping mandrel 44 shown in FIG. 9 . Forexample, the fixture device 42 may include a frame 46 attached betweenfirst mandrel segment 41 and second mandrel segment 43 and maintainfirst and second mandrel segments 41, 43 a fixed distance apart. In someinstances, frame 46 may include an adjustment mechanism (e.g., anadjustment screw) which may allow a user to adjust the distance betweenthe first mandrel segment 41 and the second mandrel segment 43 to adesired fixed distance. Additionally, adjusting the distance between thefirst mandrel segment 41 and the second mandrel segment 43 may alsoalter their distance from the compressive member 45. The distancebetween the first mandrel segment 41 and the second mandrel segment 43may control the shape of the first tapered region 17 and the secondtapered region 19 described above with respect to FIG. 2 .

FIG. 10 illustrates a cross-sectional view of the shaping mandrel 44shown in FIG. 9 . FIG. 10 shows shaping mandrel 44 removed from thefixture device 42 described above. As described above, FIG. 10 showsshaping mandrel 44 including first mandrel segment 41, second mandrelsegment 43 and compressive member 45 (positioned between first mandrelsegment 41 and second mandrel segment 43). As described above, FIG. 10shows that the compressive member 45 may include a narrowed aperture 52(e.g., opening, pinch point, etc.). It can be appreciated that thenarrowed aperture 52 of compressive member 45 may be utilized to formthe narrowed region 11 of the tubular scaffold 22 shown in FIG. 1 . Thenarrowed region 11 of tubular scaffold 22 of FIG. 1 may be referred toas a “necked” region. Additionally, FIG. 10 illustrates that shapingmandrel 44 may include a first raised annular rim 48 and a second raisedannular rim 48. First annular rim 48 may be provided with first mandrelsegment 41 and second annular rim 48 may be provided with second mandrelsegment 43. As will be shown and described below with respect to FIG. 11, first and second raised annular rims 48 may be utilized to form theenlarged portions 12 or flanges of the tubular scaffold 22 shown in FIG.1 . Furthermore, fixture device may include a first saddle 47 and asecond saddle 49 configured to be placed around the first mandrelsegment 41 and the second mandrel segment 43, respectively, to clamp abraided tubular scaffold to the shaping mandrel 44. For instance, afirst end region of the braided tubular scaffold can be clamped betweenthe first saddle 47 and the first mandrel segment 41 and a second endregion of the braided tubular scaffold can be clamped between the secondsaddle 49 and the second mandrel segment 43.

An example method to form tubular scaffold 22 may include positioning astraight, cylindrical tubular braided scaffold around shaping mandrel 44(shown in FIG. 11 ) followed by the application of a heat treatment toanneal the stent filaments 14 (shown in FIG. 11 ) in a preferred shape(e.g., the shape dictated by the shaping mandrel 44). For example, FIG.11 illustrates an example cylindrical tubular braided scaffold 56 whichhas been positioned (e.g., disposed) around first mandrel segment 41 andsecond mandrel segment 43, having first and second end regions clampedto the first and second mandrel segments 41, 43 with first and secondsaddles 47 and 49, respectively. Braided tubular scaffold 56 may beformed from one or more interwoven filaments 14 formed into acylindrical structure. FIG. 11 further illustrates braided scaffold 56disposed along first mandrel segment 41 and second mandrel segment 43,with raised annular rims 48 positioned in the lumen of the braidedscaffold 56 such that filaments 14 of braided scaffold 56 conform to thecurvature/shape of the raised annular rims 48. It can be appreciatedthat first saddle or clamp 47 and second saddle or clamp 49 may bedesigned to grasp and hold the braided scaffold 56 along the outersurface of both first mandrel segment 41 and second mandrel segment 43,respectively. Additionally, first saddle or clamp 47 may be positionedproximate the first raised annular rim 48 to instill a first ridgeportion 57 in the braided scaffold 56 and second saddle or clamp 49 maybe positioned proximate the second raised annular rim 48 to instill asecond ridge portion 59 in the braided scaffold 56. Both first ridgeportion 57 and second ridge portion 59 may extend radially away fromother portions of braided scaffold 56. Additionally, both first ridgeportion 57 and second ridge portion 59 may extend circumferentiallyaround the outer surface of braided segment 56.

It can be appreciated from FIG. 11 that the shape of each of first ridgeportion 57 and second ridge portion 59 may define a particular shape ofthe tubular scaffold 22 after a heat treatment is applied to the braidedcylindrical scaffold 56. For example, after heat treating the braidedscaffold 56 shown in FIG. 11 , the first ridge portion 57 and secondridge portion 59 may correspond to the enlarged portions or flanges 12of the tubular scaffold 22 shown in FIGS. 1 and 2 . Similarly, it can beappreciated that the outer diameter of first end portion 21 and secondend portion 23 of the tubular scaffold 22 shown in FIGS. 1 and 2 maycorrespond to the outer diameter of first mandrel segment 41 and secondmandrel segment 43 shown in FIG. 11 .

FIG. 11 further illustrates that shaping mandrel 44 may form a narrowed(e.g., necked) region in braided scaffold 56 by passing stent filaments14 through the narrowed aperture 52 of the compressive member 45. Forexample, FIG. 11 illustrates filaments 14 tapering radially inward fromfirst mandrel segment 41 to the narrowed aperture 52 and taperingradially inward from second mandrel segment 43 to the narrowed aperture52, with filaments of braided scaffold 56 extending through narrowedaperture 52. In some instances, one or more dies of compressive member45 may be actuated radially inward to radially constrain filaments 14 ofbraided scaffold 56 at narrowed aperture 52 to a reduced diameter, withtapered portions 60 and 62 on either side of compressive member 45. Thecompressive member 45 may restrain the diameter of the braided scaffold56 at the necked region to a diameter of D_(c) or less of the finishedstent 10, as described above. Additionally, it can be appreciated thatfirst tapered portion 60 of braided scaffold 56 and second taperedportion 62 of the braided scaffold 56 may correspond to first taperedregion 17 and second tapered region 19 of the tubular scaffold 22 ofstent 10 shown in FIG. 1 .

With the filaments 14 of the tubular braid scaffold 56 held in a desiredconfiguration with the shaping mandrel 44, the tubular braid scaffold 56can be subjected to a heat treatment process to anneal the stentfilaments 14 in a preferred formed shape. Thereafter, the braidedscaffold 56 may be removed from the shaping mandrel 44, while retainingits formed shape to be used as the tubular scaffold 22 of the stent 10.

It can further be appreciated that the configuration that braidedscaffold 22 embodies after being removed from the shaping mandrel 44 maybe considered its “nominally deployed” configuration. In other words,the heat treatment process applied to the braided scaffold 56 during theforming process described above may impart a shape-memory configurationin which the scaffold 22 will revert to when unconstrained by anexternal force. This shaped memory configuration may be referred to asthe stent's “nominally deployed” configuration. For example, if scaffold22 is radially expanded to a diameter greater than its “nominallydeployed” diameter, it will return to its “nominally deployed” diameteronce the force which is maintaining the scaffold in the radiallyexpanded configuration is removed. The nominally deployed configurationis important because it may define the threshold radial force impartedby the stent filaments 14 to maintain valve 16 in a closedconfiguration. As discussed above, this threshold force is the force forwhich the peristaltic contractions must overcome in order to open thevalve 16. Correspondingly, it provides the force imparted onto the valve16 to bias the valve in the closed configuration to ensure stomach acidscannot leak back through the valve from the stomach (while a patient islying down at rest, for example).

FIG. 12 shows method further process for constructing coating layer 20and valve 16 within braided scaffold 22 (after braided scaffold 56 hasbeen removed from shaping mandrel 44 as described above). As shown inFIG. 12 , after being removed from the shaping mandrel 44, braidedscaffold 22 may be positioned on a coating mandrel 61. The coatingmandrel 61 may be constructed of multiple components to facilitateinserting the coating mandrel 61 into the lumen of the tubular scaffold22 and through the narrowed region. For example, a first member of themandrel 61 may be inserted into the lumen of the tubular scaffold 22from a first end of the tubular scaffold 22 and a second member of themandrel 61 may be inserted into the lumen of the tubular scaffold 22from a second end of the tubular scaffold 22. For instance, coatingmandrel 61 may include a female member 66 coupled to a male member 64.The male member 64 may include a screw member 74 that may be threadedinto a female threaded recess 75 located in female member 66, forexample. It can be appreciated that this male-female connection mayallow coating mandrel 61 to be easily separated and removed aftercoating material 65 is applied to braided scaffold 22.

In some instances, the outer diameter of coating mandrel 61 may belarger than the inner diameter of braided scaffold 22 being positionedthereon. It can be appreciated that designing coating mandrel 61 to havea larger outer diameter versus inner diameter of scaffold 22 may resultin the scaffold 22 being positioned snug against the outer surface ofcoating mandrel 61 (FIG. 12 shows scaffold 22 being positioning snug onthe outer surface of coating mandrel 61). Further, the larger outerdiameter of coating mandrel 61 (as compared to the inner diameter ofscaffold 22) may “radially expand” the scaffold 22 as compared to its“nominally deployed” configuration (e.g., nominally deployed diameter)as discussed above. Namely, the coating mandrel 61, extending throughthe narrowed region 11, radially expands the tubular scaffold 22 at thenarrowed region to a diameter greater than its diameter D_(C) in thenominally deployed configuration in which the valve 16 is in the closedconfiguration. As will be discussed further with respect to FIG. 13 , itcan be appreciated that after coating mandrel 61 is removed from thescaffold 22 (after applying the coating layer to the scaffold 22),scaffold 22 may radially compress to its “nominally deployed”configuration (determined via the heat treatment process described abovewith respect to FIG. 11 ) to bias the valve 16 to the closedconfiguration.

Further, it can be appreciated that coating mandrel 61 may be a varietyof shapes and/or configurations. For example, coating mandrel 61 mayhave a profile which substantially matches the profile of the tubularscaffold 22 being positioned thereon. FIG. 12 shows coating mandrel 61including a profile which substantially matches the profile of thescaffold 22.

FIG. 12 shows spraying element 63 applying a spray coating 65 toscaffold 22 with coating mandrel 61 extending within lumen of scaffold22. The layer of material applied to scaffold 22 may correspond tocoating layer 20 described in the examples above. Further, as shown inFIG. 12 , spraying element 63 may translate the full length of scaffold22 while rotating tubular scaffold 22 and coating mandrel 61 together,depositing material corresponding to coating layer 20 accordingly.

It can further be appreciated that the shape of coating mandrel 61 maydefine the shape of valve 16. For example, it can be appreciated thatspray 65 may pass through the cells of scaffold 22, forming a layer ofmaterial on the inner surface of scaffold 22 at locations where scaffold22 is spaced away from coating mandrel 61. For instance, the detailedview of FIG. 12 shows coating mandrel 61 including a recessed portion 67spacing the surface of coating mandrel 61 away from tubular scaffold 22at narrowed region 11. Recessed portion 67 may also be referred to as a“reservoir.” Further, recessed portion 67 may extend circumferentiallyaround the entire circumference of coating mandrel 61. Recessed portion67 may facilitate the formation of a portion of coating layer 20 thatextends radially inward from the inner surface of tubular scaffold 22.Accordingly, the shape/contour of coating layer 20 forming the valve 16may be determined by the profile of recessed portion 67. For example,the cross-sectional shape of recessed portion 67 may be substantiallyovular. It can be appreciated that the ovular shape created by recessedportion 67 may correspond to the ovular valve aperture 24 describedabove. Thus, valve 16 may be formed in the open configuration during thecoating process.

FIG. 12 shows that in some instances, the outer surface of coatingmandrel 61 will be positioned and/or aligned substantially “flush” withthe inner surface of scaffold 22. Depositing coating layer 65 alongportions of coating mandrel 61 which are substantially flush with theinterior surface of scaffold 56 may cause coating layer 20 to adhere toand/or form an integral interface with the inner surface of tubularscaffold 22 with the coating layer 20 filling open cells or intersticesof tubular scaffold 22. As discussed above, applying spray 65 alongportions of coating mandrel 61 which are not substantially flush withthe interior surface of scaffold 22 (e.g., recessed portion 67) mayresult in spray 65 passing through the cell openings of scaffold 22 andbeing deposited along the surfaces coating mandrel 61. It can beappreciated that the recessed portions 67 of coating mandrel 61 mayallow space for spray 65 to extend radially inward beyond the innersurface of scaffold 22 such that the coating layer 20 is moldedaccording to the shape of the recessed portion 67. It can be furtherappreciated from FIG. 12 that coating layer 20 applied along surface ofrecessed portion 67 may, therefore, form the radially inward extendingportions of valve 16 (including ovular aperture 24) described above.

FIG. 13 shows scaffold 22 after coating mandrel 61 (e.g., coatingmandrel 61 described with respect to FIG. 12 ) has been removed. Asdiscussed above, components of mandrel 61 (i.e., first and secondmembers 64, 66) may be separated to remove coating mandrel 61 from lumenof tubular scaffold 22 to provide stent 10 including scaffold 22 andcoating layer 20. For instance, male member 64 may be unscrewed from thefemale member 66 and separated therefrom.

As described above, after stent 10 is removed from coating mandrel 61,tubular scaffold 22 may radially compress and return to its “nominallydeployed” configuration. In other words, filaments 14 may radiallycompress narrowed region 11 inward to return the scaffold 22 to itsnominally deployed configuration described above and collapse the valve16 to its closed configuration. Valve 16 may be formed from adeflectable and/or compressible material which would deform as coatingmandrel 61 is removed from scaffold 22. For example, after valve 16 hasbeen constructed according to the method described with respect to FIG.12 , its flexibility may permit the valve aperture 24 (described abovebut not shown in FIG. 12 ) to close in response to scaffold 22 radiallycompressing and returning to its nominally deployed configuration.

FIG. 14 illustrates an example stent delivery system 80. Stent deliverysystem may be utilized to advance and position the stent 10 describedabove. Accordingly, stent delivery system may include a handle member 81coupled to an outer tubular member 82 and/or an inner member 83. Theinner member 83 may extend through the lumen of outer tubular member 82and is depicted as a dotted line extending through a lumen of outertubular member 82). The inner member 83 may be coupled to a tip member84.

FIG. 15 illustrates stent 10 positioned over (e.g., surrounding) theinner member 83 (it is noted that the outer tubular member 82 maysurround a portion of stent 10 and is shown in a partially retractedconfiguration for simplicity). As will be described in greater detailbelow, the inner member 83 may extend through the lumen of stent 10(including the valve aperture 24 described above). It can further beappreciated that the handle member 81 may be utilized to retract theouter tubular member 82 relative to stent 10, inner member 83 and tipmember 84 to deploy the stent 10.

As shown in FIG. 15 , the tip member 84 may include one or more taperedportions 85 designed to allow the tip to be easily retracted backthrough the lumen of stent 10 after stent 10 has been deployed at atarget site. This feature is important because valve 16 of stent 10 maybe radially compressed on inner member 83 when loaded on the innermember 83 with the inner member 83 extending through valve 16.Therefore, tapered portions 85 are designed to minimize chance that tipmember 84 may engage and interfere with the positioning of stent 10 astip member 84 is retracted through the lumen of stent 10, and throughvalve 16.

FIG. 16 is a cross-sectional view taken along line 16-16 of FIG. 15 . Asdescribed above, FIG. 16 shows stent 10 including filaments 14encircling valve 16. Valve 16 may extend radially inward from the innersurface of the filaments 14 and includes an ovular valve aperture 24through which the inner member 83 extends. As described above, valve 16of stent 10 may be radially compressed on the inner member 83 in its“nominally deployed” configuration. In this configuration, the valve 16(via the filaments 14) may exert a radially compressive force onto thesurface of the inner member 83.

As discussed above with respect to FIG. 1 , FIG. 3 and FIG. 4 , valve 16may expand radially outward to allow a bolus of nutritional material(e.g., food) 18 to pass through the lumen of stent 10 and through valve16. Further, as discussed with respect to FIG. 2 , in some instances itmay be desirable for the valve 16 to expand radially outward to permitnutritional material (e.g., food, water, etc.) to pass through the lumenof stent 10. For example, the stent filaments of tubular scaffold 22which impart a radially compressive force inward on valve 16 maymaintain the valve 16 in a closed configured while in a“nominally-deployed” state (e.g., a state in which no outside forces areacting on the stent 10 to move the valve 16 to an open configuration).However, the compressive force exerted by filaments 14 of tubularscaffold 22 on valve 16 must be low enough such that normal, peristalticcontractions associated with normal digestive processing (e.g., normaleating and digesting of food) will open valve 16, thereby permitting thebolus of nutritional material to pass through valve 16 and into thestomach (while also permit vomiting contractions to expel food backthrough valve 16.

To that end, when designing stent 10 (shown in FIG. 1 ), it may bebeneficial to understand the radially outward forces generated by abolus of nutritional material passing through portions of stent 10. Forexample, it may be beneficial to understand the minimum radially outwardforces generated by a bolus of nutritional material passing through thenarrowed region 11 of the stent 10. It can be appreciated from the abovediscussion that the minimum radially outward forces generated by thebolus of material passing through the narrowed region 11 of the stent 10may correspond to the maximum compressive forces exerted by filaments 14of the tubular scaffold 22 on the valve 16. For example, in someinstances that stent 10 may be designed such that the maximumcompressive forces exerted by filaments 14 of tubular scaffold 22 onvalve 16 must be low enough to permit the minimum radially outward forcegenerated by bolus of material to pass through the stent 10. Forinstance, the stent 10 may be designed such that the maximum radiallycompressive force exerted by the filaments 14 of tubular scaffold 22 onvalve 16 to close the valve 16 in a nominally-deployed state are lessthan the minimum radially outward force generated by a bolus of materialpassing through the stent 10, in order to ensure the valve 16 openssufficiently to allow the bolus of material to pass through the stent10.

FIG. 17 illustrates an example bolus force test fixture 90. The testfixture 90 may be utilized to determine the radially outward forcesgenerated by a representative bolus of material passing through thestent 10. As shown in FIG. 17 , the test fixture 90 may include a firststent engagement member 94 a and a second stent engagement member 94 b,each of which are secured to a base 92. The first stent engagementmember 94 a and the second stent engagement member 94 b may be alignedwith one another along a longitudinal axis 93. As illustrated in FIG. 17, each of the first stent engagement member 94 a and the second stentengagement member 94 b may be secured to the base 92 via a firstengagement mount or strap 97 a (utilized to secure the first stentengagement member 94 a to the base 92) and a second engagement mount orstrap 97 b (utilized to secure the second stent engagement member 94 bto the base 92).

Each of the first and the second stent engagement members 94 a, 94 b maybe shaped such that they are designed to engage the first end 21 and thesecond end 23 of the stent 10 (not shown in FIG. 17 , but shown in FIG.1 ). For example, each of the first and the second stent engagementmembers 94 a, 94 b may include a first protrusion 95 a (extendingradially outward from the outer surface of the stent engagement member94 a) and a second protrusion 95 b (extending radially outward from theouter surface of the stent engagement member 94 a). It can beappreciated that the shape of each of the first engagement member 94 aand the second engagement member 94 b may be designed to mate with thefirst end 21 and the second end 23 of the stent 10 (not shown in FIG. 17, but shown in FIG. 1 ). For example, the first protrusion 95 a and thesecond protrusion 95 b may each be designed to mate with the enlargedportions 12 of the stent 10.

Additionally, FIG. 17 illustrates that each of the first stentengagement member 94 a and the second stent engagement member 94 b mayinclude a first lumen 92 a and a second lumen 92 b, respectively. It canbe appreciated that each of the first lumen 92 a and the second lumen 92b may be designed (e.g., sized) such that a bolus member 96 may passtherethrough. The bolus member 96 may resemble a spherically shaped balldesigned to mimic (e.g., resemble, etc.) a bolus of nutritional materialwhich may pass through the stent 10 (shown in FIG. 1 ). While FIG. 17illustrates that bolus member 96 spherically-shaped, other shapes arecontemplated to mimic various types of nutritional material passingthrough the stent 10.

Further, FIG. 17 illustrates that the bolus member 96 may be attached toa pull member 98 which may be designed to pass through the first lumen92 a and the second lumen 92 b of the first stent engagement member 94 aand the second stent engagement member 94 b, respectively. In otherwords, it can be appreciated that the pull member 98 may be utilized topull the bolus member 96 along the axis 93 through each of the firststent engagement member 94 a and the second stent engagement member 94b, and thus through the valve 16 of a stent 10 mounted to the fixture90.

FIG. 18 and FIG. 19 illustrate the example bolus member 96 being pulledthrough the stent 10 described above. In particular, FIG. 18 illustratesthe first end 21 of the stent 10 mounted to the first engagement member94 a and the second end 23 of the stent 10 mounted to the secondengagement member 94 b. Further, as described above, FIG. 18 illustrateseach of the first engagement strap 97 a and a second engagement strap 97b securing the first engagement member 94 a and the second engagementmember 94 b to the base 92.

Additionally, FIG. 18 illustrates the bolus member 96 aligned with thefirst lumen 94 a along the axis 93. Further, the pull member 98 isattached to the bolus member 96 while also extending through the firstlumen 92 a of the first engagement member 94 a, the stent 10 (includingthe narrowed region 11) and through the second lumen 92 b of the secondengagement member 94 b.

FIG. 19 illustrates the bolus member 96 being pulled through the stent10. In particular, FIG. 19 illustrates bolus member 96 being pulledthrough the narrowed region 11 of stent 10. It can be appreciated thatto measure the radially outward forces generated by the bolus member 96as the bolus member 96 is pulled through the stent 10, one or morecomponents of the testing fixture 90 may be attached (e.g., gripped,clamped, supported, etc.) to a force measurement machine (e.g., atensile testing machine, Instron® machine, etc. It is noted that, forsimplicity, the force testing machine is not shown in FIG. 18 or FIG. 19). For example, in some instances, the base 92 may be secured to oneportion of the force testing machine while the pull member 98 may beattached to another portion of the force testing machine.

Further, the force testing machine may be designed to “pull” the pullmember 98 (which is attached to the bolus member 96) through the stent10, as indicated by the arrow 99 in FIG. 19 . As the pull member 98pulls the bolus member 96 through the stent 10 (e.g., through thenarrowed region 11 of stent 10 as shown in FIG. 19 ), the force testingmachine may continuously record the radially outward forces generated bythe bolus member 96 as it advances through the stent 10, as a functionof the axial force measured. It can be appreciated that the speed withwhich the bolus member 96 is pulled through the stent 10 may be variedto better understand how the stent reacts (e.g., the force variationsplaced upon the stent 10) as the bolus member 96 passes through thestent 10 at varying speeds.

In some instances, the test methodology described above has shown thatthe radially outward forces generated by the bolus member 96 having adiameter of 15 mm may be in the range of between 2.40 N to 4.70 N as thebolus member 96 is pulled through the stent 10 at a speed of 5 mm/s, inthe range of between 2.20 N to 3.40 N as the bolus member 96 is pulledthrough the stent 10 at a speed of 7 mm/s, in the range of between 2.20N to 3.30 N as the bolus member 96 is pulled through the stent 10 at aspeed of 10 mm/s, in the range of between 2.00 N to 3.30 N as the bolusmember 96 is pulled through the stent 10 at a speed of 12 mm/s, and inthe range of between 2.0 N to 3.30 N as the bolus member 96 is pulledthrough the stent 10 at a speed of 15 mm/s, for example. Thus, in suchan instance, the filaments 14 should exert a radially inward compressiveforce of less than 2.0 N, less than 1.5 N, or less than 1.0 N in anominally deployed state to ensure that the valve 16 will opensufficiently to permit a bolus of material to pass through the valve 16.

It should be understood that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of steps without exceeding the scope of thedisclosure. This may include, to the extent that it is appropriate, theuse of any of the features of one example embodiment being used in otherembodiments. The disclosure's scope is, of course, defined in thelanguage in which the appended claims are expressed.

What is claimed is:
 1. An expandable stent, comprising: a tubularscaffold formed of one or more interwoven filaments, the tubularscaffold defining a lumen and including an inner surface and an outersurface; and a flexible valve extending radially inward from the innersurface of the tubular scaffold; wherein the one or more filaments ofthe scaffold are configured to shift the flexible valve from an openconfiguration to a closed configuration; wherein the one or morefilaments are biased radially inward to hold the flexible valve in theclosed configuration while in a nominally deployed state.
 2. The stentof claim 1, wherein the valve is configured to shift from the closedconfiguration to the open configuration due to a peristaltic forceapplied to the tubular scaffold.
 3. The stent of claim 1, wherein thevalve includes a valve opening extending therethrough, and wherein thevalve opening is ovular-shaped in the open configuration.
 4. The stentof claim 1, where the tubular scaffold includes a narrowed region andthe valve is positioned in the narrowed region.
 5. The stent of claim 1,wherein the one or more filaments of the scaffold are configured toradially expand to shift the valve from the closed configuration to theopen configuration when subjected to a radial expansion force of 0.200N/cm² or greater.
 6. The stent of claim 1, wherein the one or morefilaments of the scaffold are configured to radially expand to shift thevalve from the closed configuration to the open configuration whensubjected to a radial expansion force of 0.800 N/cm² or greater.
 7. Thestent of claim 1, further comprising a coating disposed along the one ormore filaments, and wherein the valve is formed from a portion of thecoating.
 8. The stent of claim 7, wherein the tubular scaffold has afirst end, a second end, and a length extending therebetween, whereinthe coating extends along an entirety of the length of the tubularscaffold.
 9. The stent of claim 7, wherein the coating extends alongonly the inner surface of the tubular scaffold.
 10. The stent of claim7, wherein the coating extends along both the inner and outer surfacesof the tubular scaffold.
 11. The stent of claim 1, wherein the valve isan annular member extending continuously around the lumen of the tubularscaffold.
 12. The stent of claim 1, wherein the tubular scaffold has anhourglass shape with a narrowed waist in the closed configuration,wherein the valve is disposed within the narrowed waist.
 13. The stentof claim 12, wherein the one or more interwoven filaments are heat setin the hourglass shape.
 14. The stent of claim 1, wherein the one ormore interwoven filaments form one or more flanges defining regions ofincreased diameter.
 15. An expandable stent, comprising: a tubularscaffold formed of a plurality of interwoven filaments, the tubularscaffold including a first end, a second end and a lumen extendingtherethrough; and a flexible valve defined within the lumen; wherein theplurality of interwoven filaments are configured to move the flexiblevalve from an open configuration to a closed configuration; wherein theplurality of interwoven filaments apply a radially compressive force onthe valve to bias the valve in the closed configuration while the stentis in a nominally deployed state.
 16. The stent of claim 15, wherein thetubular scaffold includes a narrowed region positioned between the firstend and the second end, wherein the valve is formed in the narrowedregion.
 17. The stent of claim 15, wherein the radially compressiveforce is less than or equal to 0.800 N/cm2.
 18. The stent of claim 15,further comprising a coating disposed along the plurality of filaments,and wherein the valve is formed from a portion of the coating.
 19. Anexpandable stent, comprising: a tubular scaffold having a first end, asecond end, and defining a lumen extending therebetween; and a flexiblevalve extending radially inward from the inner surface of the tubularscaffold; wherein the tubular scaffold is configured to shift theflexible valve from an open configuration to a closed configuration;wherein the tubular scaffold is biased to hold the valve in the closedconfiguration while in a nominally deployed state.
 20. The stent ofclaim 19, wherein the tubular scaffold includes a narrowed regionpositioned between the first and second ends, and wherein the valve ispositioned in the narrowed region.